Strangely enough, I have recently been in the same position with one of my clients. We were testing different email body content but found a huge difference in open rates between the two variants - as far as open metrics were concerned (from name, subject line, preview text etc) these was exactly the same for version A and B - the difference was the header image and intro text within the email itself. We ran the test 3 times a week over a month, so we had a decent set of data to analyse.
The conclusion we came to was that perhaps as the header content was different, what users could see in the preview pane was also having an influence on opens as well as the subject line, from name, etc. In some email clients you can have a preview pane set up a bit like Outlook desktop.
However, it is difficult to say for sure as we don't know which recipients have preview pane enabled in their email clients and those who don't. But this was something we thought may have had an impact!
I work with various clients, so have inherited a number of different naming conventions but generally they are centered around the data and subject matter. This makes reporting easy and straight forward whether you are looking at campaigns in Google Analytics, in an exported spreadsheet or in the ESP:
E0001-210616-subject-here (where E0001 is the campaign number used internally by the client)
One of my new clients uses Asana to manage their email process, and I am really enjoying using it. Each campaign is set up as a task, and within that you have sub tasks that are assigned to various users across the business and agency - designer to create assets, buyer to check stock, agency to build and test, etc. At any one time you can log in and see where you are at with any campaign. All sub tasks are assigned to a user with a deadline, regular emails are sent out to assigned users with their task lists. The original brief and all images assets are uploaded to the platform and within the task, and conversations can happen within each task so everything is all kept within one place.
I have been noticing [message clipped] a lot more recently, but I just assumed it was because I was opening a lot more Groupon/Wowcher style emails, which tend to be quite long. I just checked a few of those and one of them is 97kb and has been clipped by Gmail.
I would be interested to hear what others use too, as I am starting to do a lot more of this kind of thing! So far I have found the Pardot Nurturing Lab to be a great resource, definitely worth a look if you have not seen it already - http://www.pardot.com/nurturing-lab/